The history of Peytoia is somewhat confused and entangled with that of Laggania (another name for Peytoia) and Anomalocaris: all three were initially identified as isolated body parts and only later discovered to belong to a single type of animal. This was due in part due to their makeup of a mixture of mineralized and unmineralized body parts; the mouth and feeding appendage was considerably harder and more easily fossilized than the delicate body. The first was a detached 'arm', described by Joseph Frederick Whiteaves in 1892 as a crustacean-like creature due to its resemblance to the tail of a lobster or shrimp. The first fossilized mouth was discovered by Charles Doolittle Walcott, who mistook it for a jellyfish and placed it in the genus Peytoia. The body was discovered separately and classified as a sponge in the genus Laggania; the mouth was found with the body, but was interpreted by its discoverer Simon Conway Morris as an unrelated Peytoia that had through happenstance settled and been preserved with the "Laggania". Later, while clearing what he thought was an unrelated specimen, Harry B. Whittington removed a layer of covering stone to discover the unequivocally connected arm thought to be a shrimp tail and mouth thought to be a jellyfish. Whittington linked the two species, but it took several more years for researchers to realize that the continuously juxtaposed Peytoia, Laggania and feeding appendage actually represented a single, enormous creature. According to International Commission on Zoological Nomenclature rules, the oldest name takes priority, which in this case would be Peytoia.